The act is the verb. The agent is the noun. The substrate is the ground. Every entry on the timeline above is an occupant of the same seat, exercising the same conferred agency, paying the same per-act bill in joules. The history is the history of fluency expanding across occupants — not the history of agency being invented.
The arrival of language-model runtimes is the addition of a new occupant to a seat with a long roster. The framework that locates them is the same framework that locates init in 1971, cron in 1975, make in 1976, systemd in 2010. The substrate is unchanged. The ceiling is unchanged. The floor is unchanged. Only the occupant’s fluency profile has rotated.